[CentOS] New messages in journalctl

The following messages have started to appear in the system log after
the most recent update of my Centos7 machine

gnome-software-service.desktop[3389]: 20:54:22:0879 Gs  no app for changed places-menu at gnome-shell-extensions.gcampax.github.com
gnome-software-service.desktop[3389]: 20:54:22:0886 Gs  no app for changed alternate-tab at gnome-shell-extensions.gcampax.github.com
gnome-software-service.desktop[3389]: 20:54:22:0898 Gs  no app for changed launch-new-instance at gnome-shell-extensions.gcampax.github.com

Anybody knows what's it about?